The present invention relates to drilling apparatus and more particularly to valving mechanism for controlling fluid flow from one axial side of a latch body landing shoulder to the other and for forming a fluid seal with the drill string to permit the apparatus being fluidly propelled to the bit end of a drill string.
U.S. Pat. No. 5,325,930 to Harrison discloses a toggle linkage movable to a overcenter position for locking the latches in a latch seated position and for retracting the latches.
U.S. Pat. No. 5,339,915 to Laporte et al discloses a one way retention valve in a core barrel inner tube assembly that functions to retain drilling liquid pressure in lost circulation situations resulting from, for example, drilling into a cavity or into a broken earth formation. However, with such apparatus, the descent in a drill string is very slow since the fluid bypass channel is blocked and liquid can not bypass except around the exterior of the latch body landing shoulder. Further, a heavy duty spring is used to create a high liquid pressure and retain a column of liquid above the core barrel inner tube assembly. This high pressure in combination with pump surging has resulted in wear on the valve ball seat. The ball essentially hammers the seat which, over a period of time, damages the seat.
U.S. Pat. No. 5,020,612 to Williams discloses a core barrel inner tube assembly having a resilient ring (bushing) in the fluid bypass channel through which a valve ball is forced by fluid under pressure when the inner tube assembly is in its core collecting position at the bit end of the drill string.
U.S. Pat. No. 3,333,647 to Karich et al discloses a core barrel inner tube assembly having spring mechanism acting between a latch body and a latch release tube to constantly urge the latch release tube to a position permitting the latches moving to a latch seated position.
In order to make improvements in fluid bypass valving mechanism, latching mechanism and/or mechanism for incorporation in drilling apparatus to facilitate fluidly propelling a drilling tool to the bit end of a drill stringthat includes, for example, wire line core barrel tube assemblies, retractable drag bits and earth sampling tubes that are retractable through a drill string and/or an outer barrel, this invention has been made.